7 weather, climate and animal adaptations to climate


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7 weather, climate and animal adaptations to climate

  1. 1. 7 Weather, Climate and Adaptations of Animals to ClimateD o you remember the things that you were asked to pack when you were heading for a hillstation? When the sky is cloudy, yourparents insist that you carry anumbrella. Have you heard elders in yourfamily discuss the weather before Fig. 7.1 A sample of a weather report from aplanning a family function? You must newspaperhave also heard the experts discussingthe weather before the start of a game.Have you ever wondered why? The I wonder who preparesweather may have a profound effect on these reports!the game. It has a profound effect onour lives. Many of our daily activities are The weather reports are prepared byplanned based on the weather predicted the Meteorological Department of thefor that day. There are daily reports of Government. This department collectsthe weather on the television and data on temperature, wind, etc., andradio and in the newspapers. But do you makes the weather prediction.know what this weather really is? In this chapter, we will study about Activity 7.1the weather and climate. We will also Cut out the weather reports of the lastsee how different forms of life are week from any newspaper. If you do notadapted to the climate of their habitat. get a newspaper at home borrow from7.1 WEATHER your neighbours or friends and copyIn Fig. 7.1 a sample of weather report these reports in your notebook. You canfrom a newspaper is given. also collect weather reports from a We find that the daily weather report library. Paste all the cut-outs on a whitecarries information about the sheet or on a chart paper.temperature, humidity and rainfall Now record the information from theduring the past 24 hours. It also weather reports collected by you inpredicts the weather for the day. Table 7.1. The first row is just a sample.Humidity, as you might know, is a Fill all the columns according to the datameasure of the moisture in air. in the chart that you have prepared.68 SCIENCE
  2. 2. Table 7.1 Weather data of a week Date Max. Min. Min. Max. Rainfall* temp. (°C) temp. (°C) humidity (%) humidity(%) (mm) 23-08-06 36.2 27.8 54 82 *(Rainfall may not be recorded for all the days since it may not rain everyday. Leave the space for rainfall blank if the data is not available.) Rainfall is measured by an weather is too humid”, or “the weather instrument called the rain gauge. It was warm last week”. is basically a measuring cylinder with The weather is such a complex a funnel on top to collect rainwater. phenomenon that it can vary over very short periods of time. It can happen Do all the seven days have the same sometimes that it is sunny in themaximum and minimum temperatures, morning, but suddenly clouds appearhumidity and rainfall? The maximum from nowhere and it starts rainingand minimum temperatures recorded heavily. Or, a heavy rain may vanish inmay be the same for some of the days. a matter of minutes and give way toHowever, all the parameters are not the bright sunshine. You must have hadsame on any two days. Over a week there several such experiences. Try to recallmay be considerable variation. The day- any such experience and share it withto-day condition of the atmosphere your friends. Since weather is such aat a place with respect to the complex phenomenon, it is not easy totemperature, humidity, rainfall, wind-speed, etc., is called the weather at that predict.place The temperature, humidity, andplace. Look at the graph given below whichother factors are called the elements of shows the maximum temperaturethe weather. The weather of a place recorded during 03 August 2006 to 09changes day after day and week after August 2006 at Shillong, Meghalayaweek. That is why we often say, “today’s (Fig. 7.2).WEATHER, CLIMATE AND ADAPTATIONS OF ANIMALS TO CLIMATE 69
  3. 3. Date Maximum temperature 03-08-06 26.0°C 04-08-06 23.5°C 05-08-06 25.0°C 06-08-06 22.0°C 07-08-06 25.5°C 08-08-06 23.3°C 09-08-06 24.4°C Fig. 7.2 Graph showing the variation of maximum temperature during 03 to 09 August 2006 As it is clear from any weather report, that there are special thermometers forthe maximum and minimum this purpose, called maximum andtemperatures are recorded every day. Do minimum thermometers Can you thermometers.you know how these temperatures are guess when during the day we have therecorded. In Chapter 4 you have learnt maximum temperature and when the minimum? The maximum temperature of the day occurs generally in the afternoon while I wonder why weather the minimum temperature occurs changes so frequently! generally in the early morning. Can you now understand why in summers we feel What is the source of weather so miserable in the afternoon and in the first place? comparatively comfortable early in the morning? All changes in the weather are caused by the sun The sun is a huge sphere of sun. hot gases at a very high temperature. The distance of the sun from us is very large. Even then the energy sent out by the sun is so huge that it is the source of all heat and light on the earth. So, the sun is the primary source of energy that causes changes in the weather. Energy absorbed and reflected by the earth’s surface, oceans and the atmosphere play important roles in determining the weather at any place. If you live near the sea, you would have realised that the weather at your place is different from that of a place in a desert, or near a mountain.70 SCIENCE
  4. 4. What about the times of sunrise and of the time, then we say that the climatesunset? You know that in winters it of that place is hot. If there is also heavybecomes dark early and you do not get rainfall on most of the days in the samemuch time to play. Are the days shorter place, then we can say that the climatein winter than in summer? Try to find of that place is hot and wet.it out yourself by completing the project In Table 7.2 and 7.3, we have givengiven at the end of the chapter. the climatic condition at two places in India. The mean temperature for a given7.2 CLIMATE month is found in two steps. First weMeteorologists record the weather every find the average of the temperaturesday. The records of the weather have recorded during the month. Second, webeen preserved for the past several calculate the average of such averagedecades. These help us to determine the temperatures over many years. Thatweather pattern at a place. The average gives the mean temperature. The twoweather pattern taken over a long places are: Srinagar in Jammu andtime, say 25 years, is called the Kashmir, and Thiruvananthapuram inclimate of the place. If we find that Kerala.the temperature at a place is high most Table 7.2 Srinagar (Jammu & Table 7.3 Thiruvananthapuram Kashmir) (Kerala) Information about climate Information about climate Month Mean temperature Mean Month Mean temperature Mean o C total o C total Daily Daily rainfall Daily Daily rainfall minimum maximum (mm) minimum maximum (mm) Jan -2.3 4.7 57 Jan 22.2 31.5 23 Feb -0.6 7.8 65 Feb 22.8 31.9 24 Mar 3.8 13.6 99 Mar 24.1 32.6 40 Apr 7.7 19.4 88 Apr 24.9 32.6 117 May 10.7 23.8 72 May 24.7 31.6 230 Jun 14.7 29.2 37 Jun 23.5 29.7 321 July 8.2 30.0 49 July 23.1 29.2 227 Aug 17.5 29.7 70 Aug 23.2 29.4 138 Sep 12.9 27.8 33 Sep 23.3 30.0 175 Oct 6.1 21.9 36 Oct 23.3 29.9 282 Nov 0.9 14.7 27 Nov 23.1 30.3 185 Dec -1.6 8.2 43 Dec 22.6 31.0 66(Note: The numbers for the mean total rainfall have been rounded off)WEATHER, CLIMATE AND ADAPTATIONS OF ANIMALS TO CLIMATE 71
  5. 5. By looking at Tables 7.2 and 7.3 we habitats. As examples of adaptation ofcan easily see the difference in the animals to climatic conditions, weclimate of Jammu & Kashmir and discuss only animals living in polarKerala. We can see that Kerala is very regions and tropical rainforests.hot and wet in comparison to Jammu As the name suggests, the polar& Kashmir, which has a moderately hot regions are situated near the poles, i.e.,and wet climate for a part of the year. north pole and south pole. Similar data for the western region Some well-known countries thatof India, for example Rajasthan, will belong to the polar regions are Canada,show that the temperature is high Greenland, Iceland, Norway, Sweden,during most part of the year. But during Finland, Alaska in U.S.A. and Siberianwinter, which lasts only for a few region of Russia.months, the temperature is quite low. Examples of some countries whereThis region receives very little the tropical rainforests are found arerainfall. This is the typical desert India, Malaysia, Indonesia, Brazil,climate. It is hot and dry. The north- Republic of Congo, Kenya, Uganda, andeastern India receives rain for a major Nigeria.part of the year. Therefore, we can say Activity 7.2that the climate of the north-east is wet wet. Take an outline map of the world. Mark7.3 CLIMATE AND ADAPTATION the polar regions in blue. Similarly,Climate has a profound effect on all mark the tropical regions in red.living organisms. Animals are adapted to survive in the (i) The polar regionsconditions in which they live. Animals The polar regions present an extremeliving in very cold and hot climate must climate. These regions are covered withpossess special features to protect snow and it is very cold for most part ofthemselves against the extreme cold or the year. For six months the sun doesheat. Recall from Chapter 9 of your not set at the poles while for the otherClass VI science book the definition of six months the sun does not rise. Inadaptation. Features and habits that winters, the temperature can be as lowhelp animals to adapt to their as –37°C. Animals living there havesurroundings are a result of the process adapted to these severe conditions. Letof evolution. us see how they are adapted by In Chapter 9 you will learn about the considering the examples of polar bearseffect of weather and climate on soil. and penguins.Here we study the effect of climate on Polar bears have white fur so thatanimals only. In Class VI, you have read they are not easily visible in the snowyabout adaptations of animals to certain white background. It protects them from72 SCIENCE
  6. 6. their predators. It also helps them in Another well-known animal living incatching their prey. To protect them the polar regions is the penguinfrom extreme cold, they have two thick (Fig. 7.4). It is also white and mergeslayers of fur. They also have a layer of well with the white background. It alsofat under their skin. In fact, they are so has a thick skin and a lot of fat to protectwell-insulated that they have to move it from cold. You may have seen picturesslowly and rest often to avoid getting of penguins huddled together. This theyoverheated. do to keep warm. Recall how warm you Physical activities on warm days feel when you are in a hall full of people.necessitate cooling. So, the polar beargoes for swimming. It is a goodswimmer. Its paws are wide and large,which help it not only to swim well butalso walk with ease in the snow. Whileswimming under water, it can close itsnostrils and can remain under water forlong durations. It has a strong sense ofsmell so that it can catch its preyfor food. We can understand the Fig. 7.4 Penguins huddled togetheradaptations of polar bears with the helpof the flow chart shown in Fig. 7.3. Fig. 7.3 Adaptations of polar bearWEATHER, CLIMATE AND ADAPTATIONS OF ANIMALS TO CLIMATE 73
  7. 7. long, birds must remain warm to survive. They migrate to warmer regions when winter sets in. They come back after the winter is over. You know probably that India is one of the destinations of many of these birds. You Fig. 7.5 Feet of penguin must have seen or heard about theLike polar bears, penguins are also good Siberian crane that comes from Siberiaswimmers. Their bodies are streamlined to places like Bharatpur in Rajasthanand their feet have webs, making them and Sultanpur in Haryana, and somegood swimmers (Fig. 7.5). Other animals living in the polarregions are many types of fishes, muskoxen, reindeers, foxes, seals, whales, Do fishes and butterfliesand birds. It is to be noted that while also migrate like birds?fish can remain under cold water for Fig. 7.6 Migratory birdsin their habitat/ Migratory birds in flight Did you know?Some migratory birds travel as much as 15000 km to escape the extreme climaticconditions at home. Generally they fly high where the wind flow is helpful andthe cold conditions allow them to disperse the heat generated by their flightmuscles. But how these birds travel to the same place year after year is still amystery. It seems that these birds have a built–in sense of direction and know inwhich direction to travel. Some birds probably use landmarks to guide them. Manybirds may be guided by the sun during the day and stars at night. There is someevidence that birds may use the magnetic field of the earth to find direction. Andit is not only birds that migrate; mammals, many types of fish and insects arealso known to migrate seasonally in search of more hospitable climates.74 SCIENCE
  8. 8. wetlands of north east and some otherparts of India (Fig. 7.6).(ii) The tropical rainforestsThe tropical region has generally a hotclimate because of its location around Fig. 7.7 Red-eyed frogthe equator. Even in the coldest monththe temperature is generally higher thanabout 15°C. During hot summers, thetemperature may cross 40°C. Days andnights are almost equal in lengththroughout the year. These regions getplenty of rainfall. An important featureof this region is the tropical rainforests.Tropical rainforests are found inWestern Ghats and Assam in India,Southeast Asia, Central America andCentral Africa. Because of continuouswarmth and rain, this region supportswide variety of plants and animals. Themajor types of animals living in therainforests are monkeys, apes, gorillas, Fig. 7.8 A new world monkeylions, tigers, elephants, leopards, lizards,snakes, birds and insects. are such that they can easily hold on to Let us read about the adaptations of the branches.these animals to a hot, humid climate. As there is competition for food, some The climatic conditions in rainforests animals are adapted to get food notare highly suitable for supporting an easily reachable. A striking example isenormous number and variety of that of the bird Toucan (Fig. 7.9), whichanimals. possesses a long, large beak. This helps Since the numbers are large, there a toucan to reach the fruits on branchesis intense competition for food and which are otherwise too weak to supportshelter. Many animals are adapted to its weight.living on the trees. Red-eyed frog Many tropical animals have sensitive(Fig. 7.7) has developed sticky pads on hearing, sharp eyesight, thick skin andits feet to help it climb trees on which it a skin colour which helps them tolives. To help them live on the trees, camouflage by blending with themonkeys (Fig. 7.8) have long tails for surroundings. This is to protect themgrasping branches. Their hands and feet from predators. For example, big catsWEATHER, CLIMATE AND ADAPTATIONS OF ANIMALS TO CLIMATE 75
  9. 9. (Fig. 7.11). It has adapted to the conditions of rainforests in many remarkable ways. Look at its trunk. It uses it as a nose because of which it has a strong sense of smell. The trunk is also used by it for picking up food. Moreover, its tusks are modified teeth. These can tear the bark of trees that elephant loves to eat. So, the elephant is able to handle the competition for foodFig. 7.9 Toucan Fig. 7.10 Lion-tailed macaque rather well. Large ears of the elephant help it to hear even very soft sounds.(lions and tigers) have thick skins and They also help the elephant to keep coolsensitive hearing. in the hot and humid climate of the The lion-tailed macaque (also called rainforest.Beard ape) lives in the rainforests ofWestern Ghats (Fig. 7.10). Its mostoutstanding feature is the silver-whitemane, which surrounds the head fromthe cheeks down to its chin. It is a goodclimber and spends a major part of itslife on the tree. It feeds mainly on fruits.It also eats seeds, young leaves, stems,flowers and buds. This beard ape alsosearches for insects under the bark ofthe trees. Since it is able to get sufficientfood on the trees, it rarely comes downon the ground. Another well-known animal of Indiantropical rainforest is the elephant Fig. 7.11 An Indian elephant Keywords Adaptation Maximum temperature Tropical rainforest Climate Migration Tropical region Elements of weather Minimum temperature Weather Humidity Polar region76 SCIENCE
  10. 10. What you have learnt The day-to-day condition of the atmosphere at a place with respect to the temperature, humidity, rainfall, wind-speed, etc., is called the weather at that place. The weather is generally not the same on any two days and week after week. The maximum temperature of the day occurs generally in the afternoon while the minimum temperature occurs in the early morning. The times of sunrise and sunset also change during the year. All the changes in the weather are driven by the sun. The average weather pattern taken over a long time, say 25 years, is called the climate of the place. The tropical and the polar regions are the two regions of the earth, which have severe climatic conditions. Animals are adapted to the conditions in which they live. The polar regions are very cold throughout the year. The sun does not set for six months in a year and in the other six months it does not rise. Animals in the polar region are adapted to the extremely cold climate by having some special characteristics such as white fur, strong sense of smell, a layer of fat under the skin, wide and large paws for swimming and walking, etc. Migration is another means to escape the harsh, cold conditions. Because of the hospitable climatic conditions huge populations of plants and animals are found in the tropical rainforests. Animals in the tropical rainforests are adapted such that they eat different kinds of food to overcome the competition for food and shelter. Some adaptations of animals living in the tropical rainforests include living on the trees, development of strong tails, long and large beaks, bright colours, sharp patterns, loud voice, diet of fruits, sensitive hearing, sharp eyesight, thick skin, ability to camouflage in order to protect themselves from predators, etc. Exercises 1. Name the elements that determine the weather of a place. 2. When are the maximum and minimum temperature likely to occur during the day? 3. Fill in the blanks: (i) The average weather taken over a long time is called ___________.WEATHER, CLIMATE AND ADAPTATIONS OF ANIMALS TO CLIMATE 77
  11. 11. (ii) A place receives very little rainfall and the temperature is high throughout the year, the climate of that place will be ___________ and ___________ . (iii) The two regions of the earth with extreme climatic conditions are ___________ and __________. 4. Indicate the type of climate of the following areas: (a) Jammu and Kashmir: _________________________________ (b) Kerala: ____________________________________________ (c) Rajasthan: __________________________________________ (d) North-east India: _____________________________________ 5. Which of the two changes frequently, weather or climate? 6. Following are some of the characteristics of animals: (i) Diets heavy on fruits (ii) White fur (iii) Need to migrate (iv) Loud voice (v) Sticky pads on feet (vi) Layer of fat under skin (vii) Wide and large paws (viii) Bright colours (ix) Strong tails (x) Long and large beak For each characteristic indicate whether it is adaptation for tropical rainforests or polar regions. Do you think that some of these characteristics can be adapted for both regions? 7. The tropical rainforest has a large population of animals. Explain why it is so. 8. Explain, with examples, why we find animals of certain kind living in particular climatic conditions. 9. How do elephant living in the tropical rainforest adapt itself. Choose the correct option which answers the following question: 10. A carnivore with stripes on its body moves very fast while catching its prey. It is likely to be found in (i) polar regions (ii) deserts (iii) oceans (iv) tropical rainforests 11. Which features adapt polar bears to live in extremely cold climate? (i) A white fur, fat below skin, keen sense of smell. (ii) Thin skin, large eyes, a white fur. (iii) A long tail, strong claws, white large paws. (iv) White body, paws for swimming, gills for respiration.78 SCIENCE
  12. 12. 12. Which option best describes a tropical region? (i) hot and humid (ii) moderate temperature, heavy rainfall (iii) cold and humid (iv) hot and dry Extended Learning — Projects and Activities 1. Collect weather reports of seven successive days in the winter months (preferably December). Collect similar reports for the summer months (preferably June). Now prepare a table for sunrise and sunset times as shown: Table June December Date Sunrise Sunset Date Sunrise Sunset Try to answer the following questions: (i) Is there any difference in the time of sunrise during summer and winter? (ii) When do you find that the sun rises earlier? (iii) Do you also find any difference in the time of sunset during the month of June and December? (iv) When are the days longer? (v) When are the nights longer? (vi) Why are the days sometimes longer and sometimes shorter? (vii) Plot the length of the day against the days chosen in June and December. (Instructions for plotting graphs are given in Chapter 13.) 2. Collect information about the Indian Meteorological Department. If possible visit its website: http//www.imd.gov.in. Write a breif report about the things this department does. Did you know? Rainforests cover about 6% of the earth’s surface, but they have more than half of the animal life and about two-thirds of the flowering plants of the planet. However, much of this life is still unknown to us.WEATHER, CLIMATE AND ADAPTATIONS OF ANIMALS TO CLIMATE 79